An electric fan usually includes a set of blades having a curved configuration each. The set of blades is driven by a driving motor to rotate, so that air is sucked into the fan from one side of the blades and then blown out of the fan from the other side of the blades to thereby produce airflow toward a target object. However, the blades can only produce linearly moved airflow. To direct the linearly moved airflow produced by the fan to different directions, an oscillating mechanism must be additionally provided for the fan.
According to the oscillating mechanisms thereof, the currently available fans can be generally divided into two types, namely, a cover-rotating fan and an oscillating fan.
The cover-rotating fan includes an air guiding mechanism arranged at a front side of the overall fan structure. The air guiding mechanism normally includes a plurality of parallelly spaced tilted slats. When the air guiding mechanism is rotated, the originally linearly moved airflow produced by the fan meets the rotating tilted slats and is automatically directed to different flowing directions to thereby produce a widened breezy area.
To achieve the purpose of directing the airflow to different directions, the tilted slats of the air guiding mechanism for the fan are usually densely arranged. Dust tends to accumulate in the small spaces between the densely arranged tilted slats, and the densely arranged tilted slats would adversely restrict the range of airflow to result in lowered cooling efficiency.
The oscillating fan is a fan provided in a base thereof with a rotary mechanism for producing an oscillating motion of the fan. That is, the rotary mechanism reciprocatingly rotates a main shaft of the fan to thereby change the direction of the produced airflow. When the oscillating fan operates, the whole fan oscillates about the rotary mechanism to swing to and fro sidewardly within a large span.
However, the sideward oscillation of the fan within a large span does not guide the airflow upward and downward. Therefore, the sideward oscillating fan is not suitable for some special working environment that requires vertical airflow. Further, the rotary mechanism of the oscillating fan has a gear set that is subject to wearing due to unbalanced weight undertaken by the rotary mechanism. The worn-out gear set results in a fan that tends to jig or halt during oscillating and accordingly has reduced operating efficiency and shortened service life.
On the other hand, most of the current industrial fans have metal-made blades and a powerful driving motor for rotating the blades at high speed, so as to meet the requirement of producing a large amount of airflow. The conventional oscillating fan and cover-rotating fan have a structure that fails to meet the requirement of the industrial fans. For the purpose of directing the airflow produced by the general industrial fan to different directions, the industrial fan is normally manually oriented to different directions. When orienting the industrial fan to different directions with a hand, there is a potential risk in the safety of using the industrial fan because the operator's hand might touch and be injured by the metal blades of the fan. Therefore, the conventional industrial fans have relatively low applicability.
In conclusion, the conventional fans, no matter what type of rotary mechanism is adopted, have the disadvantage of limited airflow direction or non-adjustable airflow direction. Further, the large-size industrial fans also have the problems of lacking available oscillating mechanism, uneasy to regulate airflow direction, and tending to injure the operator. Therefore, it is desirable to develop an improved oscillating mechanism for general fans.